1. Field of the Invention
The present invention relates generally to a cushioned layer that is generally applied to a floor, but can also be used on roofs or walls.
2. Description of the Related Art
A foam rubber, often referred to as cellular, sponge, or expanded rubber refers to rubber that has been manufactured with a foaming agent to create an air-filled matrix construct. Foam rubber is generally made of either polyurethane or natural latex. The main physical properties of foam rubber are lightweight, buoyant, cushioning performance, thermal and acoustic insulation, and impact dampening. Crosslinking technology is used in the formation of EVA based foams, including LLDPE, LDPE, HDPE, PP, and TPE. Crosslinking is the most important characteristic in the production of foam rubber to obtain the best possible foam expansion and physical properties. Crosslinking is defined as chemical bonding between polymer chains, and is used for foam rubber manufacturing to stabilize bubble expansion, enhanced resistance to thermal collapse and improve physical properties.
Surface coverings, particularly decorative finished flooring products, often require an underlayment to be installed over an underlying support surface, such as a wood sub-floor, concrete or other substrate. Often the underlayment layer is attached to the substrate by way of an adhesive, nails, screws, or staples. The underlayment serves as a foundation for the application of the surface coverings, and provides a clean, smooth surface upon which to position a finished floor or other surface layer. A function of the underlayment is to provide a smooth surface so that the texture or graining of the underlying surface is not transmitted through to the surface of the top layer of the flooring. Unfortunately some underlayments fail to resist loads and punctures from concentrated loads and traffic, and can contain substances that bleed through and stain the surface covering.
One manner of installing an underlayment is to use a liquid adhesive applied to the exposed surface of the underlayment, and/or to the flooring surface and then applying the underlayment and the flooring to each other. Typically, the adhesives is applied at the floor with the use of a notched trowel to spread the adhesive on the floor, which can prove to be labor intensive and often a messy process. Roll-on and spray-on adhesives are also available. The adhesives should firmly bond the surface covering to the underlayment to prevent the surface covering from buckling or curling through a wide range of wear and environmental conditions. Importantly, the adhesive should not contribute to staining of the finished flooring.
Another manner of installing underlayment is to provide an adhesive layer on the back of the surface covering itself. Pre-applied adhesives primarily have been utilized for carpet installation. For example, one installation method includes a thin scrim webbing with adhesive on both sides and a release film disposed over the adhesive on one side. Another similar method uses a carpet padding which has a pressure sensitive adhesive on both sides and a release film disposed over the adhesive on one side. The exposed adhesive is contacted with the sub-floor, and the release film is removed to expose an adhesive layer, which receives and bonds to the carpet.
A difficulty with underlayment is that the adhesive is messy and does not allow easy adjustment of the floor being applied thereover.
What is needed in the art is an overlayment that allows for adjustment of flooring pieces as it is being laid, yet increased in strength allowing an efficient cost saving installation.